A natural or human-caused disaster can impair significantly the operation of a telecommunication network element. A telecommunication network element may fail, for example, due to damage or destruction by one of several disaster events. Such disaster events include damage or destruction by fire, flood, earthquake, war, sabotage, or terrorist activity. Several scenarios, including the following, are possible: partial failure of a network element, such as a Digital Access and Cross-Connect System (DACS) frame; failure of a single network element such as a DACS; failure of multiple network elements; and failure of an entire node of network elements. DACS network elements are described generally in an article by R. P. Abbott and D. C. Koehler, "Digital Access and Cross-Connect System--System Architecture," NTC '81, IEEE, National Telecommunication Conference, vol. 1, pp. B.1.2.1-B.1.2.7 (1981). This article and all other articles, patents or texts referred to herein are incorporated by reference.
Currently, the primary method of contingency and disaster recovery relies on data stored only in each network element unit. The data's availability for disaster recovery is highly valuable for planning and recovery of a vital core network. Similarly, the data is highly valuable for planning and recovery of Presidential, government, military, and commercial private telecommunication lines travelling through network elements. Although the data about the mapping states of each circuit traversing through the network element is important for restoring the service to its original pre-disaster state, the data stored within each unit is relatively volatile and vulnerable to destruction in a disaster.
Under existing restoration methods, additional limitations are present. Specifically, restoration of a network element occurs serially, circuit by circuit. Each circuit of each network element in the affected office requires new circuit layouts before service restoration can occur. Furthermore, this step must take place prior to reestablishing cross-connections between circuits. These limitations result in long time delays before service can be restored. For example, an AT&T DACS Operations Support System (DACS-OSS) can restore circuits serially at the rate of approximately ten circuits per minute. AT&T commercially available DACS I, DACS II, and DACS II CEF network elements have approximately 1,536, 7,680, and 32,256 circuits respectively, not including any Subrate circuits. These numbers translate to current restoration periods of approximately 1-8 hours for each DACS I, 1-12 hours for each DACS II, and up to 50 hours for each DACS II CEF.
Another limitation of the existing method is that it supports like-for-like restoration only. Thus, for example, a damaged or destroyed DACS I network element must be reconstructed on a DACS I network element equipped identically to the failed element.
In addition to the above limitations, the existing process does not permit reconfiguration or rerouting of circuits.